Pheromone Monitoring for Stored Product Pests

03/2022 Issue: Pheromone Monitoring for Stored Product Pests

By: Paul Gough

Monitoring is at the heart of IPM programs. Monitors, typically in the form of various types of traps and sensors, are devices we leave behind to tell us what’s happening while we’re not there. The data they give us then tells us what we should be doing or looking for on our next service visit.

What we call “stored product pests” are insects that eat our stored dry foods and don’t need external water sources. Some feed inside whole grains, some outside; some are scavengers feeding on broken grains and processed products; and some are secondary pests that feed on deteriorated product and mold. Monitoring for these pests is essential in dry ingredient, processing, and finished product areas of food processing and storage facilities. It can also be useful in museums and many other types of facilities where dried plant and animal-based materials are used and stored.

Monitoring for stored product pests involves either sticky or “pitfall” traps that they fly or crawl into, and attractants that are either insect pheromones (chemicals the insects use to communicate) or food-based attractants.

For flying stored product pests such as Indian meal moths, cigarette beetles, and warehouse beetles, the pheromones used are those of a female who is ready to mate (called sex pheromones). These lures are placed in sticky traps that are typically hung at about eye level. Traps can be placed in a grid pattern throughout a storage area. Males are strongly attracted to these pheromones and captures give us a good indication of how many insects are nearby, up to about a 50’ radius, depending on air movement, conditions, and temperature.

For stored product pests such as flour beetles, weevils, and grain beetles, for which sex pheromones are not as attractive or not commercially available, an “aggregation” pheromone is used. These signal the insects to group together but are not nearly as attractive as sex pheromones. Aggregation pheromones are attractive up to about 10’ and work best when placed very near where insects would likely be found. These pheromones are typically placed in pitfall traps.

For other crawling SPP such as sawtooth grain beetles and secondary or fungus feeders like fungus beetles, minute brown scavenger beetles, springtails, and psocids, a food-based attractant is used in a pitfall style trap. Pitfall traps are typically placed on the floor and are designed with a ramp that leads to a slide into an area the insect can’t climb back out of and/or a substance that will entrap it. Pitfall traps can be used with a combination of pheromone and food-based attractants. These traps will also indicate the presence of other pests such as ants, clover mites, and small spiders.

Analyzing data over time from pheromone monitoring will indicate further monitor placement for triangulation of sources, target areas for in-depth inspection (for infested products, structural harborage points, and focused sanitation needs), and potential treatment points.